Real estate agents frequently use the term “retrofit” to signify whether the basement unit is or is not fully “legal.” But in this context, its use is incorrect, and only refers to fire code — one of the five requirements.

The provincial fire code is a subset of the Ontario building code. The building code applies only to the day the unit was constructed. Only the fire code is retroactive — and this gives rise to the term “retrofit.”

As a result, a unit which does not have a fire retrofit may otherwise comply with the building code, electrical safety requirements and zoning bylaws. It’s all very complicated.

In 1994, the provincial government set new fire code rules with which all basement apartments, new and existing, must comply. A unit upgraded to comply with the fire code is called a “basement retrofit.”

Compliance with the fire code involves four requirements: fire containment, means of escape, fire detection and alarms, and electrical safety.

Drywall separations between the basement and the rest of the house must have a minimum 30-minute fire rating. A separate exit (or fire-separated shared exit) is required. A basement window is acceptable if it meets certain size and location requirements.

Fire safety rules also require installation of smoke alarms in all units in a house. They do not have to be interconnected unless the fire separation to a common exit area does not have a 30-minute rating. Many municipalities also require carbon monoxide detectors.

Once a unit has been inspected and any deficiencies corrected, the fire department will issue a retrofit certificate to verify compliance.

But a unit that has been fully retrofitted may still not comply with zoning, building code and other requirements.

Identifying whether a municipality’s bylaws permit basement apartments is also important when buying a house with a basement unit. Since 1995, municipalities have had the authority to enforce their bylaws with respect to basement apartments; however, units that existed prior to November 1995 are exempt from meeting local bylaw requirements.

Silver notes that the building code, which prescribes minimum requirements for the construction of buildings, for the most part applies only to the day the house was built, and not retroactively.

As a rule, a basement apartment’s minimum ceiling height must be 6 feet 5 inches; its entrance door must be at least 32 inches by 78 inches; bathrooms require either a window or an exhaust fan; and if there is a parking spot for one of the units, there must also be a parking spot for the other unit.

Electrical safety refers to the required inspection by the Electrical Safety Authority.

Buyers of houses with basement units, and agents marketing them, should always insist on evidence that the unit was in existence in 1995. And they should find out whether the unit does or does not comply with the fire code, building code, electrical safety requirements and municipal zoning bylaws.

Full disclosure is of the utmost importance.

Bob Aaron is a sole practitioner at the law firm of Aaron & Aaron in Toronto and a board member of the Tarion Warranty Corp. Bob specializes in the areas of real estate, corporate and commercial law, estates and wills and landlord/tenant law. His Title Page column appears Saturdays in The Toronto Star and weekly on Move Smartly. E-mail bob@aaron.ca